ath9k: Fix ANI for AP mode

The commit "ath9k: Fix ANI monitoring" reverted an earlier
commit that adjusted ANI to improve performance. But, this causes
adverse effects in AP mode (as reported by Felix based on an OpenWrt
report). Use the older INI/period configuration for now until more
testing is done.

Cc: Felix Fietkau <nbd@openwrt.org>
Cc: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>